1. Technical Field
The present disclosure relates to a mobile wireless device in which antenna switching is performed.
2. Description of the Related Art
Mobile wireless devices including a plurality of switchable antennas have been developed to have improved communication quality through antenna switching.
Japanese Unexamined Patent Application Publication No. 2004-135054 discloses a mobile phone that determines if the antenna receives audio signals representing speech sounds of a person on the other end of the phone or data signals to confirm an operation mode of the mobile phone, and performs antenna switching based on the determination.
Japanese Unexamined Patent Application Publication No. 2011-160201 discloses a mobile wireless device that determines an opening state of a foldable chassis or an opening angle of the chassis to confirm which one of a voice call function and an internet connection function is being used, and performs antenna switching based on the determination.
Wearable devices including mobile wireless devices have recently been developed. The mobile wireless device is used while being partly in contact with the user's body. Here, a configuration of a wristwatch mobile wireless device that includes a main body, a microphone mounted in the main body, and an antenna element adjacent to the main body is discussed. In such a configuration, when the user uses the microphone, the antenna is positioned between the user's wrist and head. This causes the antenna performance to deteriorate. Such an effect on the antenna performance is referred to as a head proximity effect throughout the specification.
In order to reduce the head proximity effect in the wearable mobile wireless device, the microphone may be disposed on a component other than the main body to separate the microphone from the antenna element. However, if the microphone is remote from the main body, the user needs to confirm the position of the microphone before use, which may be inconvenient to the user.
Alternatively, in order to reduce the head proximity effect in the wearable mobile wireless device, the antenna element may be disposed on a component other than the main body to separate the microphone from the antenna element. However, if the antenna element is remote from the main body, a cable such as a coaxial cable is required to connect the antenna element and the main body to each other. This causes the antenna performance to deteriorate due to cable loss.
The above-described conventional technologies that are disclosed in Japanese Unexamined Patent Application Publications Nos. 2004-135054 and 2011-160201 do not solve the problem relating to the head proximity effect in the wearable mobile wireless device. The technology disclosed in Japanese Unexamined Patent Application Publication No. 2004-135054 detects the audio signals from a person on the other end of the phone for the antenna switching. It is impossible to know whether or not the head of the mobile phone user is positioned close to the mobile phone. In addition, the mobile phone and the wearable mobile wireless device are used in different ways. The technology disclosed in Japanese Unexamined Patent Application Publication No. 2011-160201 determines the opening state of a foldable chassis or the opening angle of a chassis to confirm which one of the voice call function and the internet connection function is being used. Thus, this technique cannot be used to solve the problem relating to the head proximity effect in the wearable mobile wireless device.